NumberResearchRecent prefix assignments
0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/20/2026
The Code holder is who opened each NPA-NXX prefix — not necessarily who holds the numbers. A prefix is 10,000 numbers, but under pooling its ten 1,000-number blocks are handed out individually, often to different carriers; the code holder may hold only one block, or none. The Thousands-blocks column shows how the ten blocks are really split — click which blocks → to see who holds each 1,000-number block and its last-4-digit range. Assignments are initial assignments; the current serving carrier may differ due to portability.
| Assigned | NPA-NXX | Thousands-blocks taken (last-4 opening) | Code holder | OCN | Rate center | State |
|---|---|---|---|---|---|---|
| — | 661-423 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-465 | 0XXX2XXX3XXX4XXX6XXX8XXX · 3 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | BERENDMESA | CA |
| — | 661-536 | 2XXX3XXX4XXX5XXX6XXX9XXX · 2 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | GLENNVILLE | CA |
| — | 661-548 | 2XXX3XXX4XXX7XXX8XXX · 4 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | CLFRNHTSPG | CA |
| — | 661-718 | 4XXX5XXX6XXX7XXX9XXX · 3 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-722 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-723 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-724 | 3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LAKEHUGHES | CA |
| — | 661-726 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-727 | 0XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | HI VISTA | CA |
| — | 661-728 | 1XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-729 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-762 | 3XXX4XXX5XXX9XXX · 2 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | MCKITTRICK | CA |
| — | 661-763 | 9XXX which blocks → | FRONTIER CALIFORNIA INC. | 4420 | TAFT | CA |
| — | 661-764 | 0XXX1XXX2XXX3XXX4XXX8XXX · 6 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | BUTTONWLLW | CA |
| — | 661-765 | 8XXX which blocks → | FRONTIER CALIFORNIA INC. | 4420 | TAFT | CA |
| — | 661-766 | 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | CUYAMA | CA |
| — | 661-768 | 0XXX1XXX2XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | TAFT | CA |
| — | 661-769 | 0XXX3XXX4XXX5XXX6XXX7XXX · 3 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | TAFT | CA |
| — | 661-792 | 4XXX7XXX8XXX · 2 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | MCFARLAND | CA |
| — | 661-797 | 0XXX1XXX3XXX4XXX5XXX · 3 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | LOST HILLS | CA |
| — | 661-940 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-942 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-943 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-945 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-946 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-948 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-949 | 4XXX which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
| — | 661-951 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LANCASTER | CA |
Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/20/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.